Please ASAP :( can anyone help me with these questions 15-25 im really stressed out, i have to do a wgeo project after this, hopefully anyone can help me at least with my algebra questions

What is the missing constant term in the perfect square that starts with x^2 -20x

Simplify this expression.2(10) + 2(x – 4) a. 2x + 16 b. x + 12 c. 2x + 12 d. x + 16

Write a polynomial function f of least degree that has rational coefficients, a leading coefficient of 1, and the given zeros. 3, 4+2i, 1+(sqrt)7 the answer is supposed to be: f(x)=x(^5)-13x(^4)+60x(^3)-82x(^2)- 144x+360 what am i doing wrong?